<div class="view-child">
  <h1>hello view child</h1>
  <div class="box" #box>
  	1、This is box content
  </div>
  <div class="box" #box>
  	2、This is box content
  </div>
  <div class="box" #box>
  	3、This is box content
  </div>
  <button class="btn btn-primary btn-large" (click)="togglePanel()">toggle one child panel</button>
  <app-child-panel></app-child-panel>
  <app-child-panel #panel></app-child-panel>
  <app-child-panel></app-child-panel>
  <app-child-panel *ngIf="showOnePanel"></app-child-panel>
  <app-child-panel></app-child-panel>
  <app-child-panel></app-child-panel>
</div>
